Humming on overhead paging, Cisco Callmanager 1

[NateRD25]

We are experiencing a constant humming sound coming from the over head paging speakers. We are using FXO ports on our Cisco Callmanager 9.x and paging does work when the paging number is dialed. Why would we hear a constant hum

 

[whykap]

Maybe the paging system requires a different input than an FXO port?
If you unplug the FXO does the humming go away?
What exactly are you connecting the FXO port to?

 

[NateRD25]

Unplugging the FXO port does not make the humming go away. We have the FXO port plugged into a TAMB2 unit and then from there it goes to our punch down blocks and wired up from there.

 

[whykap]

Ok so the issue is with your paging system and nothing to do with the FXO port.
Fix that before trying to connect to the TAMB and the fxo port. Humming usually means power is running through the audio leads, a wiring issue

 

[NateRD25]

That is what we are thinking because I have unplugged the TAMB unit and the humming is still albeit a little softer.

 

[gnrslash4life]

I had that on the 79xx series with firmware 8.5.3. One of the strangest bugs I have seen.

Certifications:
A+
Network+
CCENT
CCNA Voice
TVOICE
CAPPS

 

[whykap]

gnr,
did you post this on the wrong thread? How is this relevant?

 

[gnrslash4life]

A bug in the firmware was causing the constant humming over the overhead paging.

Certifications:
A+
Network+
CCENT
CCNA Voice
TVOICE
CAPPS

 

[whykap]

That's very interesting. Was the paging system somehow connected to a phone, were the phones humming as well?

 

[NateRD25]

We found our issue. There was a pair of wires going to a amp that were touching causing the hum, once maintenance ran a new pair the humming stopped.

 

[gnrslash4life]

Whykap,

Nope. Used TAMB's connected to FXO ports. Never have seen it again and I would have never tried it unless I had seen the bug listed for it.

Certifications:
A+
Network+
CCENT
CCNA Voice
TVOICE
CAPPS

 

[whykap]

gnr,
That's a good one for sure. Thanks for sharing the details.